Make output bucket brigade thread safe

Rewrote Alex Bligh's pull request so that it matches the coding style of
this project and it should now compile with MSVC, which is not C99
compliant (i.e., doesn't support mixing of statements and declarations).

Author: disconnect

mod_websocket.c

@@ -472,10 +472,22 @@ static void mod_websocket_data_framing(const WebSocketServer *server,
 {
     WebSocketState *state = server->state;
     request_rec *r = state->r;
-    apr_bucket_brigade *obb =
-        apr_brigade_create(r->pool, r->connection->bucket_alloc);
+    apr_pool_t *pool = NULL;
+    apr_bucket_alloc_t *bucket_alloc;
+    apr_bucket_brigade *obb;
 
-    if (obb != NULL) {
+    /* We cannot use the same bucket allocator for the ouput bucket brigade
+     * obb as the one associated with the connection (r->connection->bucket_alloc)
+     * because the same bucket allocator cannot be used in two different
+     * threads, and we use the connection bucket allocator in this
+     * thread - see docs on apr_bucket_alloc_create(). This results in
+     * occasional core dumps. So create our own bucket allocator and pool
+     * for output thread bucket brigade. (Thanks to Alex Bligh -- abligh)
+     */
+
+    if ((apr_pool_create(&pool, r->pool) == APR_SUCCESS) &&
+        ((bucket_alloc = apr_bucket_alloc_create(pool)) != NULL) &&
+        ((obb = apr_brigade_create(pool, bucket_alloc)) != NULL)) {
         unsigned char block[BLOCK_DATA_SIZE];
         apr_int64_t block_size;
         apr_int64_t extension_bytes_remaining = 0;

mod_websocket_draft76.c

@@ -535,6 +535,8 @@ static int mod_websocket_method_handler(request_rec *r)
                                 /* If the plugin supplies an on_connect function, it must return non-null on success */
                                 if ((conf->plugin->on_connect == NULL) ||
                                     ((plugin_private = conf->plugin->on_connect(&server)) != NULL)) {
+                                    apr_pool_t *pool = NULL;
+                                    apr_bucket_alloc_t *bucket_alloc;
                                     apr_bucket_brigade *obb;
 
                                     /* Now that the connection has been established, disable the socket timeout */
@@ -548,9 +550,9 @@ static int mod_websocket_method_handler(request_rec *r)
                                     ap_send_interim_response(r, 1);
 
                                     /* Create the output bucket brigade */
-                                    obb = apr_brigade_create(r->pool, r->connection->bucket_alloc);
-
-                                    if (obb != NULL) {
+                                    if ((apr_pool_create(&pool, r->pool) == APR_SUCCESS) &&
+                                        ((bucket_alloc = apr_bucket_alloc_create(pool)) != NULL) &&
+                                        ((obb = apr_brigade_create(pool, bucket_alloc)) != NULL)) {
                                         unsigned char block[BLOCK_DATA_SIZE], *extended_data = NULL;
                                         apr_off_t extended_data_offset = 0;
                                         apr_size_t block_size, data_length = 0, extended_data_size = 0;